Years ago LOCALS introduced white perch into Moosehead Lake in Maine. Apparently it was too long a ride to ponds or lakes where they otherwise could be found. {It wasn't that far, maybe twenty miles as a guess}. This introduction could be expected to have a devastating effect on the cold water fishery in the lake and the state did make an effort to trap them after they found out about it. Today you don't hear much about it, but the fishery isn't what it was.

This was a case of fishermen who did, or should have, known the impact willfully introduced these fish. How do you stop this sort of thing? If I recall correctly, there were only two individuals involved. This behavior is incomprehensible to me as that area depends heavily on tourism and sportsmen. They were virtually attacking the livilhood of their neighbors.